Various proposals have been made so far for methods of molding resinous hollow containers. As a typical method, an injection blow molding method has been known which comprises forming a preform (parison) by injection molding, and blow molding the preform to shape a hollow container. An injection blow molding apparatus adopting this injection blow molding method is equipped with an injection molding section and a blow molding section. With this apparatus, a preform is injection molded in the injection molding section, and transported from the injection molding section to the blow molding section, with a neck portion of the preform being held, whereafter the preform is blow molded in the blow molding section to form a hollow container. Such an injection blow molding apparatus is called, for example, a 1-stage or hot parison injection blow molding apparatus.
With the injection blow molding apparatus, a mold release failure may occur, if the preform is not mold-released after it has been cooled to a predetermined temperature in the injection molding section. For example, when the preform is released from an injection blow mold constituting the injection molding section, a mold release failure, such as elongation, break, or so-called stringiness of a gate portion, may occur.
In the blow molding apparatus, therefore, the preform is cooled, as appropriate, in the injection molding section so that the preform is at an appropriate temperature. For example, there is a blow molding apparatus in which a temperature controlled cooling medium such as cooling water is flowed through flow paths formed in a cavity mold and an injection core mold constituting the injection molding section to cool resin (preform) charged into a cavity (see Patent Document 1).